At present, customers not only have strict requirements on the appearance and quality of products, but also concern the price and usability of products. In the field of display technology, especially in the field of OLED (Organic Light-Emitting Diode) display technology, low luminous efficiencies of red, green and blue colors have become the bottle-neck of optimizing products. To fulfill customer's requirements, a new technology of arranging pixels comprising red sub-pixels (R), green sub-pixels (G), blue sub-pixels (B) and white sub-pixels (W) (that is, RGBW arrangement) has been developed. However, signal transmission interfaces such as VGA (Video Graphics Array) and DVI (Digital Visual Interface) generally transmit RGB signals. For this reason, during an image displaying process, the transmitted RGB signals need to be converted into RGBW signals for displaying by the display device in a case where the image is not distorted.
However, methods of converting RGB signals to RGBW signals in the prior art have the following problems:
(1) The brightness and contrast of displayed image are reduced, so that the display quality of the displayed image is lowered;
(2) The power consumption of light emitting devices is relatively large during the displaying process of the displayed image, so that the lifetime of the light emitting devices is reduced; and
(3) The power consumption of light emitting devices is relatively large during the displaying process of the displayed image, and thus a driving chip with relatively high cost is required, so that the manufacturing cost of products is increased.